Activating Carbon and Oxygen Bonds for Low-Temperature Thermal Decomposition of Spent Lithium-Ion Battery Cathode Materials

The temperature for complete disintegration of spent lithium-ion battery (LIB) cathode materials is typically in a range of 750-1400 °C, resulting in intensive energy consumption and high carbon emissions. Here, we promote the bond activation of oxygen in LiNi_0.5Co_0.2Mn_0.3O₂ and carbon in graphite electrodes, achieving rapid gasification and thermal decomposition of active crystals at lower temperatures in the absence of other activating agents. The activation of C and O bond leads to the storage of internal energy and the transition of the crystalline phase (single crystal to polycrystal) of the active crystals. Density functional theory modeling confirms that the CO adsorption energy is significantly higher with C_<i>a</i>-O_<i>a</i> (-3.35 eV, C and O activation) than with no activation (-1.66 eV). The differential charge results show that the bond activation model has the highest charge accumulation and consumption, improving the electron transfer. The Bader charge transfer between C_<i>a</i>-O_<i>a</i> and CO is also the largest, with a value of 0.433 |e|. Therefore, synchronous activation of C and O bonds can reduce the decomposition temperature of active crystals by 200 °C and allows a low-temperature pyrolysis recycling of retired LIB cathode materials. Our research provides a potential strategy for low-carbon recycling of retired LIBs worldwide.